What you are mainly describing here is metering (of light), not exposure compensation.
It's true that spot metering linked to the currently selected AF point is available for the 1DX only (of today's camera bodies). The 1DX has enough metering zones for this to work with any of the 61 AF points, since out of the 252 metering zones, there's one covering each specific AF point. Cameras like the 1D Mark III allows spot metering linked to AF points as well, but only to the 19 manually selectable points. The other 26 AF points on that camera are for AF assist only.
The 1DX, sporting a 100000 pixel light metering array (the one that's broken down to 252 light metering zones), can also use this array to detect faces while shooting using the optical viewfinder. If you combine that with the camera's ALO (Auto Lighting Optimizer), the camera will automatically not only try to prioritize exposure to the area where the face is detected, but also automatically apply correction to shadows in back-lit faces. This goes directly into your jpegs and/or is saved as a tag in a RAW file, so that you can apply the in-shooting detected value of compensation immediately in DPP, to see if the result is to your liking.
In addition to this, you can use iTR in combination with using all focus points at the same time, to let the camera try to detect faces and both focus and expose them correctly. Whether you'd like to trust this for a wedding I don't know - haven't tried it like that. But it works better than I had anticipated for candids.
As far as I can understand spot metering linked to the active AF point is impossible with just a firmware upgrade on a 5D Mark III - it simply doesn't have a light meter with enough granularity to cover each of the 61 AF points individually. In this case you most likely need a hardware upgrade, to the 1DX, or whatever may follow in the future.
All this is 1DX technology at the moment. What you can do on simpler camera models is to use evaluative metering, since that type of light metering is quite heavily weighted towards the active AF point. Or you have to resort to spot metering in the center and either lock that exposure with the * button as long as you need it, or set it in M mode.